The present invention concerns a device for adjusting the beam direction of a beam radiated from a stationary array of antenna elements, wherein at least two antenna element feed points are coupled to a common signal source via a feed line structure having a source connection terminal to be connected to said source and at least two feed connection terminals to be connected to said antenna element feed points, the feed line structure comprising a feed conductor line pattern disposed in a fixed planar arrangement, e.g. on a carrier plate, at a distance from and in parallel to a fixed ground plate, and a movable dielectric body located therebetween, said movable dielectric body being displaceable in parallel to the feed conductor line pattern and the ground plate so as to change the exciting phase of a signal component reaching one of the feed connection terminals. The invention also concerns a feed line structure for use in an antenna or any other device requiring a controlled adjustment of the phase difference between at least two signal components derived from a radio frequency signal generated by a common source.
A device of the kind referred to above is previously known from JP, A, 63296402. A number of triangular dielectric bodies are movable in two perpendicular directions, in each case transversely to a conductor line segment so as to enable a controlled delay of the corresponding signal component. The delay is substantially proportional to the surface portion of the triangle being in registry with the associated conductor line segment. In this way, the beam can be adjusted in two mutually perpendicular directions.
However, each triangular body has relatively small dimensions in relation to the length of each conductor line leading to a feed connection terminal. Therefore, the adjustment possibilities are rather limited. Furthermore, in case such triangular bodies with larger dimensions were to be used, the impedance of the feed line structure would be adversely affected.